Digital still cameras generate image data representative of an image of an object. The process of generating image data representative of an image of an object is often referred to simply as “imaging” or “capturing” the object. The image data is processed and output to a device that displays a replicated image of the object. For example, the replicated image of the object may be displayed on a video monitor or printed by a printer.
The digital camera focuses the image of the object onto a two-dimensional array of photodetecting elements. The photodetecting elements are relatively small and each one generates image data representative of a very small portion of the image of the object. For example, the two-dimensional array may have several million photodetecting elements that each generate image data representative of a small portion of the image of the object. The image data generated by the individual photodetecting elements is processed to recreate the image of the object. One type of photodetecting element is a charge-coupled device that outputs a voltage that is proportional to the amount of light it receives over a preselected period.
In order to improve the image generated by a digital camera, the density of photodetecting elements on the two-dimensional array is increased. The increased density of photodetecting elements increases the number of photodetecting elements that image an object, which in turn improves the quality of the image by reducing spaces between imaged portions of the object. Another method of improving the image generated by a digital camera, especially in low light conditions, is by using a long period to generate the image data. This long period of image generation is achieved by having the photodetecting elements detect light for an extended period.
One problem with photography, including digital photography, is that the image generated by the camera will be blurred if the camera moves as the photodetecting elements generate image data. For example, under ideal conditions of no movement in the digital camera relative to the object being imaged, each photodetecting element generates image data representative of a particular portion of the image of the object. If, however, the camera is moved as the image data is generated, the individual portions of the image of the object will be imaged by several photodetecting elements. Accordingly, each photodetecting element images several different portions of the image of the object, which causes the replicated image of the object to be blurred. This type of blur is referred to as motion blur.
The motion blur problem is exacerbated as the above-described imaging period is extended. The extended imaging period results in a higher probability that the camera will be moved during the imaging period, which results in a higher probability that motion blur will occur in the replicated image. Accordingly, the benefit of an extended imaging period may be offset by a higher probability of generating a blurred image. The problem of motion blur is further exacerbated by the use of more photodetecting elements to generate an image. The photodetecting elements will be smaller and receive less light. Accordingly, the exposure time of the camera must be extended in order for the smaller photodetecting elements to receive enough light to generate accurate image data.
Therefore, a need exists for a method and device for detecting and reducing motion blur in a digital image.